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MN Saleh, DL Moore, JY Lee and AF LoBuglio
Division of Hematology/Oncology, University of Alabama, Birmingham 35294.
Platelets from 24 patients with immune thrombocytopenia resistant to
standard therapy (refractory ITP), 35 patients with nonimmune
thrombocytopenia (non-ITP), and 32 normal donors were studied in regard to
platelet surface-bound IgG (PBIgG) and the ability of these platelets to be
bound by human monocytes in vitro (monocyte-platelet rosette assay).
Fourteen (58%) of the platelet samples from refractory ITP patients but
none (0%) from the non-ITP or control donors had PBIgG greater than 800
molecules IgG/platelet. Seventeen of 24 (71%) of the ITP patients had
platelets which demonstrated increased monocyte- platelet rosette formation
[rosette index (RI) greater than 2], whereas only four (11%) of the non-ITP
patients had such platelets. There was a direct correlation between PBIgG
and rosette index for the platelets from resistant ITP patients. There was
no correlation of severity of thrombocytopenia with PBIgG or rosette index.
Monocyte-platelet interaction in the presence of elevated PBIgG is mediated
through the monocyte Fc-receptor. Platelets from five of ten refractory ITP
patients with PBIgG less than 800 molecules IgG/platelet had increased
rosette formation. Monocyte-platelet interaction in the absence of
increased PBIgG may be due to small amounts of platelet surface IgG which
are still able to mediate monocyte Fc-receptor interaction or to alternate
membrane receptor interaction through the monocyte C3 receptor. Our data
underscore the pathophysiologic relevance of monocyte/macrophage-mediated
interaction in immune platelet destruction syndromes.
This article has been cited by other articles:
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| Copyright © 1989 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
